ABSTRACT
Metal-containing wastewaters represent an environmental and human health problem, but also a potential resource of valuable metals when their recovery is possible. Biological sulfate reduction is a process for the treatment of metal containing wastewaters enabling the recovery of metals as sulfidic precipitates. Metal recovery depends on the particle size of the metal sulfides, determined by the kinetics of nucleation, crystal growth and agglomeration, as well as their purity and their dewatering characteristics. Practical implementation of metal sulfide precipitation and sulfate reduction in a single unit is also challenging because these metal containing waste streams are acid and contain metals that can affect the biological process performance. The pH varies the influence of the influent macronutrients and the dissolved organic matter, present in the bioreactor, on the characteristics of the metal sulfide precipitates.
